1. Field of the Invention
The present invention relates to a memory medium using an optical disc from which information relative to image, sound, character, music, etc. previously recorded in applications of hobby, education, business, etc. is reproduced in a read-only manner, an apparatus for driving it and an apparatus for playing it back.
2. Description of the Related Art
In recent years, optical discs have been widely used as a recording/reproducing medium for information relative to image, sound, character, music, etc. Such optical discs include an optical video disc, CDV (Compact Disc Video), etc. for image, sound and music, a CD (Compact Disc) for music, a CD-ROM (Compact Disc Read-Only Memory) for computer data, a CD-I (Compact Disc Interactive) for multi-media comprising image, sound, character, music, computer data, etc.
Referring to the drawings, one example of an apparatus for driving a memory medium using the conventional optical disc mentioned above and that of an apparatus for reproducing it will be explained. Now, an English-Japanese dictionary system using CD-ROM will be taken as an example.
FIG. 7 is a block diagram showing an arrangement of the English-Japanese dictionary system using the conventional memory medium. In this figure, 201 is a CD-ROM disc serving as a memory medium; 202 is an access block; 203 is a control block; 204 is a processing block; 205 is a memory block; 206 is a memory medium driving apparatus; and 207 is a memory medium reproducing apparatus.
The operation of this system will be explained below. It is assumed that a data base of the English-Japanese dictionary is stored in CD-ROM 201 and the information retrieved therefrom is stored in memory block 205. Memory block 205 is constituted by a floppy disc and a driving device therefor, for example. Now, if a specific word is informed to processing block 204 from the exterior, processing block 204 investigates a position in CD-ROM 201 corresponding to information of the word from the retrieved information stored in memory block 205 and transfers the position information to control block 203. Control block 203 controls access block 202 to output a desired data in CD-ROM 201 and transfers it to processing block 204. The structure of CD-ROM 201, data recording format therein and method for constructing access block 202 are described in "ASCII", Vol. 10, No. 4, April 1986, pp 115-124 and Vol. 10, No. 5, May 1986, pp 105-115. Processing block 204 performs processing required to display the coded character on a screen or image plane, for example, to provide the information of the specified word. Incidentally, the above processing is performed in a manner such that a control program stored in memory block 205 is previously read out to processing block 204.
The optical disc used as a memory medium in the above arrangement has the following several disadvantages. Information to be stored is prepared beforehand. An original disc is cut to record the information therein. Then a large amount of duplicates are formed, and they are used as read-only devices. Therefore, rewriting of the content thereof and addition of new information thereto can not be carried out. The control program, which is supplied from another medium, is inconvenient to deal with, which makes ambiguous the combination with the optical disc. Even if the control program is stored in the optical disc, it is necessary to reconstruct the optical disc in order to increase the number of its versions. Further, whenever the data output from the optical disc contains an error, the data at the same address must be processed in a data error detection/correction section.